2-Hydroxy-3,4,4-trimethyl-cyclopent-2-en-1-one, a compound of formula ##STR1## belongs to the class of derivatives of cyclopentenone, which has been the object of voluminous scientific literature, especially directed to its mono-, di- and tri-methyl-substituted derivatives. Surprisingly, sofar only one of them has raised the perfumer's interest: 2-hydroxy-3-methyl-cyclopent-2-en-1-one has been described in fact as possessing a powerful sweet odor of caramel, spicy character [see S. Arctander, Perfume and Flavor Chemicals, Montclair N.J. 1969; section no. 1987]. Its use in perfumery however remains very limited, its main interest being confined to flavors formulation. Insofar as its dimethyl homologs are concerned, only their utility in the flavor field has been recognized where in fact 2-hydroxy-3,4-dimethyl-cyclopent-2-en-1-one and its corresponding 3,5- and 5,5-dimethyl derivatives are appreciated for their caramel-like, nutty and spicy gustative characters.
The prior art is totally mute about the organoleptic properties of the higher trimethyl homologs, for instance of 2-hydroxy-3,4,4-trimethylcyclopent-2-en-1-one.
We have now surprisingly discovered that this compound possesses useful odorous properties and that consequently it could be utilized very advantageously as perfume ingredient.